Sinkhole risk in Darke County, OH: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock: 100%
At or near the surface: 0%
Buried under cover: 100%

What this means before you buy

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 598 of Darke County's 598 square miles on soluble rock. With about 51,462 residents (86 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 390 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 100% under cover still counts, and how these percentages are measured.

Counties around Darke County

The nearest county rated sinkhole country is Kenton County, KY, about 83 miles south. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Randolph County, IN 20 mi west · 0% at surface
Miami County, OH 21 mi east · 0% at surface
Shelby County, OH 26 mi northeast · 0% at surface
Preble County, OH 27 mi south · 0% at surface
Wayne County, IN 28 mi southwest · under 1% at surface
Mercer County, OH 28 mi north · 3% at surface

The rock underneath

The largest mapped soluble unit here is the Lockport Dolomite (dolostone (dolomite)), Silurian in age, covering about 72% of the county. Next is the Salina Group at 11%.

Against the rest of Ohio

Darke County ranks 26 of 88 in Ohio for soluble rock at the surface, and sits above 0% of US counties on that measure.